System, method and apparatus for direct liquid-cooled axial flux electric machine with multiple pcb stators

ABSTRACT

A device has a housing and rotors rotatably coupled to the housing. Each rotor has a magnet on at least one side of the rotor. Printed circuit board (PCB) stators are located axially between the rotors and coupled to the housing. The PCB stators have layers, and each layer has coils. The number of rotors disks is equal to the number of stators plus one. The stators are interleaved with the rotors. A shaft is coupled to the rotors and the housing. The shaft has a hollow section coupled to a source of a liquid coolant through a rotary connector and to radial channels in the shaft that dispense a liquid coolant between the rotors and PCB stators. The shaft has flanges with different diameters configured to receive the rotors disks with respective matching bore diameters. In addition, the housing has a sump to collect the liquid coolant.

This application is a continuation of and claims priority to and thebenefit of both a) U.S. patent application Ser. No. 17/716,577, filedApr. 8, 2022, titled “SYSTEM, METHOD, AND APPARATUS FOR DIRECT LIQUIDCOOLED AXIAL FLUX ELECTRIC MACHINE WITH MULTIPLE PCB STATORS”, and b)U.S. patent application Ser. No. 17/227,888, filed Apr. 12, 2021, titled“SYSTEM, METHOD AND APPARATUS FOR DIRECT LIQUID-COOLED AXIAL FLUXELECTRIC MACHINE WITH PCB STATOR” the contents of which are incorporatedherein by reference in their entirety.

BACKGROUND OF THE DISCLOSURE Field of the Disclosure

This disclosure relates in general to an axial field rotary energydevice and, in particular, to a system, method and apparatus for aliquid-cooled axial flux electric machine, such as permanent magnetmotors and generators having one or more printed circuit board (PCB)stators.

Background

Many high-power density electric machines (2.0 kW/kg and higher) canhave a cylindrical rotor that is concentric to a cylindrical stator thatcarries conductive coils. The rotor can have conductive coils ormagnets. The rotor rotates about its axis of rotation that is coincidentwith the axis of the stator. The air gap between the major surfaces ofthe rotor and stator can be narrow, such as 1 mm or less). Due to theirhigh-power density, many of these machines are liquid-cooled. Thecooling method can be direct or indirect. Indirect liquid cooling can beaccomplished by having a cooling jacket carrying a liquid coolantmounted around the machine's stator, or by having cooling ducts embeddedin the machine's stator as described in U.S. Pat. No. 8,201,316. Directcooling can be achieved by spraying a coolant directly over the statorwinding of the electric machine. Some of the direct cooling methods canuse mineral or synthetic oil. When direct cooling is employed, thecoolant is directed to the coil end turns, which is the portion of thecoils that protrudes axially at both ends of the stator. It isundesirable to have the liquid coolant in the air gap because it willcause excessive drag losses in the narrow air gap.

Some axial field permanent magnet (PM) rotary devices, such as motors orgenerators, use printed circuit board (PCB) stator structures. Examplesinclude U.S. Pat. Nos. 10,141,803, 10,135,310, 10,340,760, 10,141,804and 10,186,922, each of which is incorporated herein by reference in itsentirety. These devices can include one, two or more PCB stators, suchas one PCB stator for each electrical phase of the device. Some devicesmay include a PCB stator having windings for more than one phase.

Each PCB stator can include a plurality of coils formed, for example, ina copper laminated structure of the PCB. As the device is powered,electrical currents circulate through the coils. The circulation ofcurrents through the PCB stator coils produces resistive losses, and theinteractions between those currents and external magnetic fields, andmagnetic fields produced by the currents themselves, produce eddycurrent losses. The combination of the resistive and eddy currentslosses generate heat in the PCB stator. This is an undesired effect ofthe circulation of currents in the PCB stator, as it increases thetemperature of the stator. In extreme cases, the temperature rise of thePCB stator may exceed the temperature class of the laminate used intheca stator, leading to its premature failure. Thus, it is desirable toremove heat from the PCB stator to keep its temperature below thetemperature class of the PCB laminate material.

The mechanisms for removing heat from the PCB stator can includeconduction, convection, and radiation heat transfer. Some of the heatgenerated in the coil conductors cane carried by conduction to theexternal surfaces of the PCB stator where it can be removed by a coolantflow. Air is commonly used as a coolant, however due to its low density(approximately 1.2 kg/m³), low thermal capacity (approximately 1.00kJ/kg.K) and poor thermal conductivity (0.026 W/m·K), air is not themost effective coolant. In some high-power density applications wherePCB stator losses can exceed 1,500 kW/m³, for example, air coolingbecomes less effective, limiting the power of the axial field PM rotarydevice. In those high-power density applications, coolants with higherthermal conductivity, thermal capacity and density can remove heat fromthe stator more effectively, allowing for higher power densities. Forexample, a liquid coolant (e.g., mineral oil) with a thermalconductivity of 0.15 W/m·K, thermal capacity of 1.67 kJ/kg.K and densityof 800 kg/m³ can remove heat from a PCB stator at a faster rate thanair, enabling power densities 3 times or higher than what would bepossible with air cooling, depending on coolant flow rates.

Some solutions to these problems have been proposed in the past, butthey have significant shortcomings. For example, GB2485185 discloses aPCB stator in a hermetically sealed case that contains the coolantfluid. The hermetic case forms a complicated structure that is difficultto build. When the stator must be replaced, the hermetic case must bedismantled. Moreover, the hermetic case fundamentally interferes withthe magnetic flux path between the rotor and stator, which significantlyreduces its machine power and efficiency.

For those who are skilled in the art it will become apparent that thefollowing disclosure greatly simplifies and enhances the direct coolingof axial field permanent magnet (PM) rotary devices.

SUMMARY

Embodiments of a system, method and apparatus for an axial field rotaryenergy device are disclosed. For example, the system can include adevice with a housing and rotors rotatably coupled to the housing. Eachrotor has a magnet on at least one side of the rotor. Printed circuitboard (PCB) stators are located axially between the rotors and coupledto the housing. The PCB stators have layers, and each layer has coils.The number of rotors disks is equal to the number of stators plus one.The stators are interleaved with the rotors. A shaft is coupled to therotors and the housing. The shaft has a hollow section coupled to asource of a liquid coolant through a rotary connector and to radialchannels in the shaft that dispense a liquid coolant between the rotorsand PCB stators. The shaft has flanges with different diametersconfigured to receive the rotors disks with respective matching borediameters. In addition, the housing has a sump to collect the liquidcoolant.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the features and advantages of theembodiments are attained and can be understood in more detail, a moreparticular description can be had by reference to the embodimentsthereof that are illustrated in the appended drawings. However, thedrawings illustrate only some embodiments and therefore are not to beconsidered limiting in scope as there can be other equally effectiveembodiments.

FIG. 1 is an isometric sectional view of an axial field PM rotary devicewith a PCB stator.

FIG. 2 is a schematic sectional side view of a portion of a PCB statormounted to a machine housing, showing a heat flow scheme.

FIG. 3 is a schematic diagram of a system comprising an axial field PMrotary device and a liquid coolant circulation system with a separateheat exchanger for the liquid coolant.

FIG. 4 is a schematic diagram of a system comprising an axial field PMrotary device and a liquid coolant circulation system with a coolantreservoir.

FIG. 5 is a schematic diagram of a system comprising an axial field PMrotary device and a liquid coolant circulation system with a reservoircoupled to a heat exchanger.

FIG. 6 is a sectional view of an axial field PM rotary device with PCBstator showing an embodiment of a liquid coolant circulation system.

FIG. 7 is an isometric sectional view of an axial field PM rotary devicewith PCB stator showing an embodiment of a bearing lubrication andcooling system.

FIG. 8 is sectional view of an axial field PM rotary device showing anembodiment of a liquid coolant system where the stator is clad in aprotective envelope.

FIG. 9 is a sectional side view of another embodiments of the device.

FIGS. 10A-10F are partial sectional side views of other embodiments ofthe device.

FIG. 11 is a plan view of an embodiment of a segmented stator for thedevice.

FIG. 12A is an isometric view of an embodiment of a rotor.

FIGS. 12B-12D are partial plan views of embodiments of magnets.

FIG. 13 is a sectional side view of yet another embodiment of thedevice.

DETAILED DESCRIPTION

This disclosure includes embodiments of systems comprising an axialfield PM rotary device. The device can include at least one stator, suchas a PCB stator mounted in a housing along an axis. A rotor assembly canbe rotatably mounted within the housing along the axis. The rotorassembly can have rotors on opposite axial ends of the PCB stator andcan have features that provide for the distribution of a liquid coolantover the PCB stator surfaces. The housing can have features that cancollect the liquid coolant and redirect it to a coolant circulation andcooling system that, in turn, returns the coolant back to the axialfield PM rotary device.

As shown in FIG. 1 , an embodiment of an axial field PM rotary device100, such as a motor or generator, can use a stator such as a PCB stator200. The PCB stator 200 can be located between rotor disks 300 that arecoupled to a shaft 350. The rotor disks 300 and shaft 350 can rotateabout an axis of rotation 150 and include bearings 160 coupled to ahousing 250. In FIG. 1 , the housing 250 can include two housingcomponents that are coupled together. The rotor discs 300 carry magnetsthat generate a magnetic field that interacts with electrical currentsthat flow through the PCB stator 200.

The axial field PM rotary device 100 can rely on conduction, convection,and radiation to remove heat from the PCB stator 200. FIG. 2 shows someof the heat removal mechanisms in and around the PCB stator 200, whichhas coils 210. Some of the heat generated in the conductors of the coils210 is carried by conduction 205 to the external surfaces of the PCBstator 200. This heat can be removed by a coolant flow 215 that flows inthe air gaps 305 between the stator 200 and the rotor discs 300. Otherportions of the heat generated by the stator coils 210 can be carried byother conduction 225 along the layers of the PCB stator 200 toward thearea where the PCB stator 200 is coupled to the housing 250. Heat 235can continue to be conducted through the machine housing 250 towardscooler surfaces and volumes, as illustrated in FIG. 2 .

Some axial field PM rotary devices with PCB stators may be designed toprovide high power. In such cases, the resistive and eddy current lossesassociated with the currents circulating through the conductors in thePCB stator can be high and exceed the heat removal capability of aircooling. The excess heat in high power PCB stators can cause the statorto overheat and exceed the temperature class rating of its PCB laminatematerial. For high power applications, this disclosure replaces air asthe stator cooling fluid with a liquid coolant. One example of a liquidcoolant is mineral oil. Other coolants also can be used. For example,coolants that are not electrically conductive and not corrosive can beused to cool the PCB stator, such as mineral or synthetic transmissionoil, transformer oil, silicone-based oil, and others. In someembodiments the coolant can be a mixture of water glycol, such as 60/40water-MEG or 60/40 water-PEG (polyethylene glycol).

FIG. 3 depicts an embodiment of a system where an axial field PM rotarydevice 100 is liquid cooled. The system can have a primary pump 110 thatcan provide a liquid coolant to the axial field PM rotary device 100.The liquid coolant can exit the axial field PM rotary device 100 througha drain 105 and be directed to a scavenge pump 115. From the scavengepump 115, the liquid coolant can go through a separate heat exchanger120 where the liquid is cooled to a lower temperature and returned to areservoir 130. Examples of the separate heat exchanger 120 can include aliquid-to-air or a liquid-to-liquid heat exchanger. The primary pump110, in turn, can recirculate the liquid coolant back to the axial fieldPM rotary device 100.

FIG. 4 shows an alternate embodiment of the system depicted in FIG. 3where a primary pump 110 provides a liquid coolant to the axial field PMrotary device 100. The liquid coolant can exit the axial field PM rotarydevice through a drain 105 and be directed to a scavenge pump 115, whichin turn, returns the liquid coolant directly to the reservoir 130. Thereservoir 130 can have features to remove heat from the liquid coolant,such fins 135 and/or a cooling fan 140.

FIG. 5 shows yet another embodiment of the system depicted in FIG. 3 .The primary pump 110 provides a liquid coolant to the axial field PMrotary device 100. The liquid coolant can exit the axial field PM rotarydevice 100 through a drain 105 and be directed to a scavenge pump 115,which in turn, returns the liquid coolant directly to the reservoir 130.The reservoir 130 can be coupled to a heat exchanger 120 that can removeheat from the liquid coolant. As an example, the heat exchanger 120 canbe a liquid-to-liquid heat exchanger.

Other embodiments of the systems depicted in FIGS. 3 to 5 also can havesensors. The sensors can include flow meters, thermocouples, pressuregauges, and other sensors to monitor the liquid coolant flow, pressure,and temperature. Furthermore, still other embodiments can include valvesto control the liquid coolant flow and pressure.

FIG. 6 depicts an example of an axial field PM rotary device 100 withfeatures that enable the liquid coolant circulation through the device.In the embodiment depicted in FIG. 6 , the axial field PM rotary device100 has a shaft 350 with a hollow section 355 that can be connected atthe end of the shaft 350 to a rotary connector 400. Liquid coolant canbe delivered to the axial field PM rotary device 100 via the rotaryconnector 400 and hollow section 355. The hollow section 355 can becoupled to one or more radial channels 360 that can direct and spreadthe liquid coolant radially between the static PCB stator 200 and therotating rotor discs 300. Some embodiments can have nozzles 365 coupledto the radial channels 360 that can spread and/or direct the coolantand/or control the coolant flow. In an example, once the coolant entersthe space between the rotor discs 300, it can flow radially through theair gaps 305 (i.e., one air gap 305 on each major side of the PCB stator200) between the rotor discs 300 and the PCB stator 200 to remove heatfrom the PCB stator 200, as generally depicted in FIG. 2 . The air gap305 can have a width of 1.0 mm or more, for example, which allows forthe liquid coolant to flow radially without creating excessive draglosses. The air gap 305 can be up to about 2.5 mm, in some examples.Other examples can include an air gap range of 1.1 mm (or 1.2 mm) to 2.5mm, or 1.5 mm to 2.0 mm in still other examples. Alternative embodimentscan include an air gap of up to 3.0 mm. Each of these versions can havenegligible or insignificant drag losses from the liquid coolant. Inprior art devices with narrower air gaps, however, excessive drag lossescan be 2 or more times the mechanical losses of the device.

Referring again to FIG. 6 , the liquid coolant can exit the air gaps 305at the periphery of the rotor discs 300 then flow into the space betweenthe rotor discs 300 and the interior walls of the housing 250 andcollect at a sump 260. In some examples, the liquid coolant can exit thehousing 250 through one or more drains 105. Although FIG. 6 shows twodrains 105 on opposing sides of the housing, other embodiments can haveonly one drain or more than two drains and/or can have all drains on thesame side of the housing. Furthermore, the drains 105 can be located atthe bottom side of the housing 250.

In the embodiment of FIG. 7 , the liquid coolant can be an oil which canhave the dual function of cooling the PCB stator 200 and lubricating andcooling the bearings 380 of the axial field PM rotary device 100. Insome examples, the shaft 350 can include a hollow section 355 thatextends from one end of the shaft 350 to the area under both bearings380 and the rotor discs 300. As described for the example of FIG. 6 ,the oil can enter the hollow section 355 through the rotary connector400. In addition to the radial channels 360 that distribute and dispensethe cooling oil to the space between the rotor discs 300, thisembodiment can have radial channels 370 that distribute and dispense oilto lubricate the bearings 380. The oil can flow through the bearings 380and into the housing where it can mix with the oil flow cooling thestator PCB 200. The embodiment shown in FIG. 7 can have mechanical seals390 that can retain and prevent the oil from leaking along the shaft350.

Some embodiments of the axial field PM rotary device 100 can use awater-based coolant or some other coolant that can be corrosive. FIG. 8shows an example of such an embodiment. In this version, liquid coolantenters the device through the hollow section 355 of the shaft 350 andflows radially through the radial channels 360 and nozzles 365 into thespace between the rotor discs 300. The liquid coolant continues to flowradially through the air gaps 305 between the rotor discs 300 and PCBstator 200. In some examples, the PCB stator 200 can have a cladding 260that prevents the liquid coolant from directly contacting the PCB stator200. Embodiments of the cladding 260 can completely envelop and seal thePCB stator 200 from exposure to the liquid coolant. The cladding 260 canbe formed from, for example, a thin sheet of a non-magnetic,corrosion-resistant material, such as Inconel 625, poly ether etherketone (PEEK), acrylic-based conformal coating, Parylene conformalcoating, or still other materials.

The liquid coolant can exit the air gaps 305 at the outer periphery ofthe rotor discs 300 then flow in the space between the rotor discs 300and the interior walls of the housing 250. The liquid coolant can becollected and/or recycled as described elsewhere in this disclosure.Embodiments can have internal seals 395 to prevent the liquid coolantfrom contacting the bearings 380.

Some embodiments of the axial field PM rotary device can have more thanone PCB stator, as depicted in FIG. 9 , which shows an example of adevice 1000 with three PCB stators and four rotors. The axial field PMrotary device comprises three PCB stators 1200.1, 1200.2 and 1200.3which can have layers and coils assigned to one or more electricalphases. PCB stators 1200.1, 1200.2 and 1200.3 can be coupled to ahousing 1250 which can have bearings 1380 that support a rotating shaft1350. The rotating shaft 1350 can support four rotor discs, in thisexample. Collectively, shaft 1350 and rotors disks 1300.1-1300.4constitute a rotor. Discs 1300.1 and 1300.2 are mounted outboard of PCBstators 1200.1 and 1200.3, respectively, and carry magnets 1005 on theside facing a stator. Discs 1300.3 and 1300.4 are mounted between PCBstators 1200.1 and 1200.2, and 1200.2 and 1200.3 respectively and carrymagnets 1005 on both sides of each disc. The example shown in FIG. 9 haseach PCB stator assigned to one electrical phase, however otherembodiments can have 3-phase PCB stators, or other stator-phasearrangements.

The shaft 1350 can have a cavity 1355 coupled to a rotary connector 1400that supplies a liquid coolant to the axial field PM rotary device 1000.The rotary connector 1400 can be capable of operating at high rotationalspeeds (e.g., between 7,500 and 10,000 rpm, for example). The cavity1355 is coupled to a plurality of radial channels 1360 that can directand spread the liquid coolant radially between the static PCB stators1200.1, 1200.2 and 1200.3 and the rotating rotor discs 1300.1 through1300.4. The liquid coolant can flow radially through the gaps betweenthe rotors and stators, then flow around the internal walls of housing1250, collect at a sump 1260, and exit the housing 1250 through one ormore drains 1105. In addition to the radial channels 1360, the shaft1350 can have radial channels 1370 located outboard of bearings 1380.Channels 1370 can provide a coolant flow through bearings 1380 which canhelp cool and lubricate the bearings (similarly to the embodimentdepicted in FIG. 7 ). Some embodiments may not have channels 1370providing coolant flow to the bearings 1380.

Although FIG. 9 shows an axial field PM rotary device with three statorsand four rotors, other embodiments of device 1000 can have two statorsand three rotors, or more generally, N stators and M rotors where M=N+1.

FIG. 10A shows a schematic view of device 1000 where the housing 1250has been removed for clarity. In FIG. 10A, the shaft 1350 of the device1000 comprises flanges 1310.1 through 1310.4 that have differentdiameters. In the example shown in FIG. 10A, flange 1310.1 has a largerdiameter than all other flanges and is coupled to rotor disk 1300.1.Flange 1310.3 is coupled to rotor disk 1310.3 and has a smaller diameterthan flange 1310.1, but larger than flange 1310.4. Flange 1310.4 iscoupled to rotor disk 1300.4 and has a diameter smaller than flange1310.3, but larger than flange 1310.2. Finally, flange 1310.2 has adiameter smaller than all other flanges and is coupled to rotor disk1300.2. The embodiment depicted in FIG. 10A, allows for the sequentialassembly of rotor disk 1300.1, PCB stator 1200.1, rotor 1300.3, PCBstator 1200.2, rotor 1300.4, PCB stator 1200.3 and rotor 1300.2 from thesame end 1351 of the shaft 1350, which can enable an automated assemblyprocess.

Some embodiments of device 1000 can have between the rotor disks1300.1-1300.4 and the corresponding shaft flanges 1310.1-1310.4, shims1301 with different thicknesses that can be added or removed to adjustthe axial position of the rotor disks relative to PCB stators andtherefore to adjust air gaps 1305 (FIG. 10A).

FIG. 10B shows a detail of the embodiment shown FIG. 10A, where theradial channels 1360 are substantially aligned axially with the PCBstators 1200.1 through 1200.3. In this embodiment the coolant flow thatemerges from the radial channel 1360 can split in two streams that flowradially in the air gaps 1305 between PCB stator 1200.1 and rotors1300.1 and 1300.3, for example. In the embodiment shown in FIGS. 10A and10B, the PCB stator inner edge 1205 has a flat edge substantiallyperpendicular to the faces of the PCB stator 1200.1.

FIG. 10C shows another embodiment where the PCB stator inner edge 1205has a substantially wedge shape that can further help split the coolantflow in two streams and direct them towards the air gaps 1305.

FIGS. 10D and 10E shows yet other embodiments where the radial channels1360 in shaft 1350 are substantially aligned with air gaps 1305. In theembodiment shown in FIG. 10D, the PCB stator inner edge 1205 can have aflat edge substantially perpendicular to the faces of the PCB stator1200.1. In the embodiment shown in FIG. 10E, the PCB stator inner edge1205 has a substantially wedge shape that can help direct the coolantflow towards the air gaps 1305.

In some embodiments of the axial field rotary device 1000, the rotordisks 1300 can have a profile that helps direct the coolant flow. FIG.10F shows an example of such embodiment were the rotor disks 1300.1 and1300.3 have a tapered profile 1302 inbound of magnets 1005. In thisembodiment, the tapered profile 1302 helps to direct the coolantdispensed through the radial channels 1360 towards the air gaps 1305 andprotect the inner edges of magnets 1005 from direct exposure to thecoolant flow.

In some embodiments of the of the axial field PM rotary device 1000, theradial channels 1360 of the shaft 1350 can have different cross sectionsto adjust the coolant flow going into the volumes delimited by adjacentrotor disks. In other embodiments, the channels 1360 of the shaft 1350can have nozzles similar to the nozzles 365 shown in FIGS. 6, 7 and 8 toadjust the coolant flow going into the said volumes.

The coolant that flows through the axial field PM rotary device 1000 canbe, for example, a mineral oil based coolant, or a water based coolant.In embodiments that employ water based coolants, the PCB stators canhave a cladding similar to the cladding 260 shown in FIG. 8 to preventdirect contact between the PCB stator and the coolant. In thoseembodiments, the bearings 1380, shown in FIG. 9 , can be sealed and thechannels 1370 can be absent.

The PCB stators 1200.1 to 1200.3 depicted in FIGS. 9 and 10A can be madeof a single laminated stack of prepreg and copper foil layers, howeverin some applications the PCB stator can be segmented as the stator 1200depicted in FIG. 11 , which has 4 segments that can be mechanically andelectrically coupled together. Other embodiments of stator 1200 can havea different number of segments.

FIG. 12A shows an embodiment of an individual rotor disk 1300 of device1000. In this embodiment, the rotor disk can carry a plurality ofalternating polarity magnets 1005.1 and 1005.2 where magnets 1005.1 canbe oriented as north poles and magnets 1005.2 can be oriented as southpoles, for example. Although the embodiment shown in FIG. 12A has a16-pole magnet arrangement, other embodiments can have different numberof magnets.

FIGS. 12B-12D show details of different embodiments of magnetarrangements of rotor disk 1300. FIG. 12B shows the orientation ofmagnets 1005.1 and 1005.2 depicted in FIG. 12A where magnet 1005.1 isoriented as a north pole and magnet 1005.2 is oriented as a south pole.This magnet pattern orientation is repeated around the whole rotor disk1300.

In other embodiments of rotor disk 1300, the magnets can be arranged ina Halbach array with two magnets per pole. FIG. 12C shows an example ofsuch magnet arrangement. In this embodiment magnet 1005.1 is split intotwo segments: 1005.1.1 and 1005.1.2 with substantially the same angularspan. Segment 1005.1.1 is oriented as a north pole and segment 1005.1.2is oriented in a direction perpendicular to magnet 1005.1.1 orientationwith its north pole pointing to magnet 1005.1.1. Similarly, magnet1005.2 is split in two segments: 1005.2.1 and 1005.2.2 withsubstantially the same angular span. Segment 1005.2.1 is oriented as asouth pole and segment 1005.2.2 is oriented in a direction perpendicularto magnet 1005.2.1 orientation with its north pole pointing away frommagnet 1005.2.1. This magnet pattern orientation is repeated around thewhole rotor disk 1300.

FIG. 12D shows another embodiment of magnets forming a Halbach array onrotor disk 1300. In this embodiment magnet 1005.1 is split into foursegments: 1005.1.1 to 1005.1.4 with substantially the same angular span.Segment 1005.1.1 is oriented as a north pole and segment 1005.1.2 isoriented in a direction perpendicular to magnet 1005.1.1 orientationwith its north pole pointing to magnet 1005.1.1. Segments 1005.1.3 and1005.1.4 are interspersed between segments 1005.1.1. and 1005.1.2 andoriented at approximately 45 degrees from the orientation of magnet1005.1.1 with their north poles pointing to magnet 1005.1.1. Similarly,magnet 1005.2 is split in four segments: 1005.2.1 to 1005.2.4 withsubstantially the same angular span. Segment 1005.2.1 is oriented as asouth pole and segment 1005.2.2 is oriented in a direction perpendicularto magnet 1005.2.1 orientation with its north pole pointing away frommagnet 1005.2.1. Segments 1005.2.3 and 1005.2.4 are interspersed betweensegments 1005.2.1. and 1005.2.2 and oriented at approximately 45 degreesfrom the orientation of magnet 1005.2.1 with their north poles pointingaway from magnet 1005.2.1. This magnet pattern orientation is repeatedaround the whole rotor disk 1300.

The magnet configuration depicted in FIG. 12A and detailed in FIG. 12Bcan include a rotor disk 1300 made of a soft magnetic material such as alow carbon steel alloy, such as A36, or SAE 4140, for example, as therotor disk carries the magnetic flux produced by the magnets. TheHalbach array magnet configurations depicted in FIGS. 12C and 12D mayinclude a rotor disk 1300 made of non-magnetic material as the magneticflux is channeled through the magnets themselves. Thus, other materialscan be used for the rotor disks 1300 based on their strength to weightratio or other properties. Some embodiments can have rotor disks made ofcarbon fiber composite. Other embodiments can have rotor disks made ofaluminum alloy, such as Aluminum 6061-T6, or titanium alloys such asTitanium Grade 9 3AL-2.5V, for example.

Some embodiments of the axial field PM rotary device 1000 can haveinductors connected in series with the PCB stators 1200.1-1200.3. FIG.13 shows one example of an embodiment of the axial field PM rotarydevice 1000 where an inductor 1500 is coaxially mounted inside thehousing 1250, so the inductor can also be cooled by the coolantdispersed inside the housing 1250 through the radial channels 1360 ofthe shaft 1350. In other embodiments, the shaft 1350 can have anadditional set of radial channels 1361 assigned to provide a coolantflow to cool the inductor 1500.

The terminology used herein is for the purpose of describing particularexamples and is not intended to be limiting. As used herein, thesingular forms “a,” “an,” and “the” may be intended to include theplural forms as well, unless the context clearly indicates otherwise.The terms “comprises,” “comprising,” “including,” and “having,” areinclusive and therefore specify the presence of stated features,integers, steps, operations, elements, and/or components, but do notpreclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof. The method steps, processes, and operations described hereinare not to be construed as necessarily requiring their performance inthe particular order discussed or illustrated, unless specificallyidentified as an order of performance. It is also to be understood thatadditional or alternative steps may be employed.

When an element or layer is referred to as being “on,” “engaged to,”“connected to,” or“coupled to” another element or layer, it may bedirectly on, engaged, connected or coupled to the other element orlayer, or intervening elements or layers may be present. In contrast,when an element is referred to as being “directly on,” “directly engagedto,” “directly connected to,” or “directly coupled to” another elementor layer, there may be no intervening elements or layers present. Otherwords used to describe the relationship between elements should beinterpreted in a like fashion (e.g., “between” versus “directlybetween,” “adjacent” versus “directly adjacent,” etc.). As used herein,the term “and/or” includes any and all combinations of one or more ofthe associated listed items.

Although the terms first, second, third, etc. may be used herein todescribe various elements, components, regions, layers and/or sections,these elements, components, regions, layers and/or sections should notbe limited by these terms. These terms may be only used to distinguishone element, component, region, layer or section from another region,layer or section. Terms such as “first,” “second,” and other numericalterms when used herein do not imply a sequence or order unless clearlyindicated by the context. Thus, a first element, component, region,layer or section discussed below could be termed a second element,component, region, layer or section without departing from the teachingsof the example embodiments.

Spatially relative terms/such as “inner/” “outer/” “beneath,” “below”“lower/” “above” “upper,” “top”, “bottom,” and the like, may be usedherein for ease of description to describe one element's or feature'srelationship to another element(s) or feature(s) as illustrated in thefigures. Spatially relative terms may be intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the example term “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated degrees or at other orientations) and the spatially relativedescriptions used herein interpreted accordingly.

This written description uses examples to disclose the embodiments,including the best mode, and also to enable those of ordinary skill inthe art to make and use the invention. The patentable scope is definedby the claims, and can include other examples that occur to thoseskilled in the art. Such other examples are intended to be within thescope of the claims if they have structural elements that do not differfrom the literal language of the claims, or if they include equivalentstructural elements with insubstantial differences from the literallanguages of the claims.

In the foregoing specification, the concepts have been described withreference to specific embodiments. However, one of ordinary skill in theart appreciates that various modifications and changes can be madewithout departing from the scope of the invention as set forth in theclaims below. Accordingly, the specification and figures are to beregarded in an illustrative rather than a restrictive sense, and allsuch modifications are intended to be included within the scope ofinvention.

It can be advantageous to set forth definitions of certain words andphrases used throughout this patent document. The term “communicate,” aswell as derivatives thereof, encompasses both direct and indirectcommunication. The terms “include” and “comprise,” as well asderivatives thereof, mean inclusion without limitation. The term “or” isinclusive, meaning and/or. The phrase “associated with,” as well asderivatives thereof, can mean to include, be included within,interconnect with, contain, be contained within, connect to or with,couple to or with, be communicable with, cooperate with, interleave,juxtapose, be proximate to, be bound to or with, have, have a propertyof, have a relationship to or with, or the like. The phrase “at leastone of,” when used with a list of items, means that differentcombinations of one or more of the listed items can be used, and onlyone item in the list can be needed. For example, “at least one of: A, B,and C” includes any of the following combinations: A, B, C, A and B, Aand C, B and C, and A and Band C.

Moreover, various functions described herein can be implemented orsupported by one or more computer programs, each of which is formed fromcomputer readable program code and embodied in a computer readablemedium. The terms “application” and “program” refer to one or morecomputer programs, software components, sets of instructions,procedures, functions, objects, classes, instances, related data, or aportion thereof adapted for implementation in a suitable computerreadable program code. The phrase “computer readable program code”includes any type of computer code, including source code, object code,and executable code. The phrase “computer readable medium” includes anytype of medium capable of being accessed by a computer, such as readonly memory (ROM), random access memory (RAM), a hard disk drive, acompact disk (CD), a digital video disk (DVD), solid state drive (SSD),or any other type of memory. A “non-transitory” computer readable mediumexcludes wired, wireless, optical, or other communication links thattransport transitory electrical or other signals. A non-transitorycomputer readable medium includes media where data can be permanentlystored and media where data can be stored and later overwritten, such asa rewritable optical disk or an erasable memory device.

Also, the use of “a” or “an” is employed to describe elements andcomponents described herein. This is done merely for convenience and togive a general sense of the scope of the invention. This descriptionshould be read to include one or at least one and the singular alsoincludes the plural unless it states otherwise.

The description in the present application should not be read asimplying that any particular element, step, or function is an essentialor critical element that must be included in the claim scope. The scopeof patented subject matter is defined only by the allowed claims.Moreover, none of the claims invokes 35 U.S.C. § 112(f) with respect toany of the appended claims or claim elements unless the exact words“means for” or “step for” are explicitly used in the particular claim,followed by a participle phrase identifying a function.

Benefits, other advantages, and solutions to problems have beendescribed above with regard to specific embodiments. However, thebenefits, advantages, solutions to problems, and any feature(s) that cancause any benefit, advantage, or solution to occur or become morepronounced are not to be construed as a critical, required, sacrosanctor an essential feature of any or all the claims.

After reading the specification, skilled artisans will appreciate thatcertain features which are, for clarity, described herein in the contextof separate embodiments, can also be provided in combination in a singleembodiment. Conversely, various features that are, for brevity,described in the context of a single embodiment, can also be providedseparately or in any sub-combination. Further, references to valuesstated in ranges include each and every value within that range.

We claim:
 1. An axial field rotary energy device, comprising: a housing;rotor disks having an axis of rotation and rotatably coupled to thehousing, and each rotor disk comprises a magnet on at least one side ofthe rotor disk; one or more printed circuit board (PCB) stators locatedaxially between the rotor disks and coupled to the housing, each PCBstator comprises layers, and each layer comprises coils, wherein anumber of the rotor disks is equal to a number of the PCB stators plusone, and the PCB stators are interleaved with the rotor disks; a shaftcoupled to the rotor disks and the housing, the shaft has a hollowsection configured to be coupled to a source of a liquid coolant and toradial channels in the shaft that are substantially aligned withrespective air gaps between the PCB stators and the rotor disks todispense the liquid coolant between the rotor disks and PCB stators; andthe shaft has flanges to receive the rotor disks.
 2. The device of claim1, wherein the radial channels that dispense the liquid coolant aresubstantially aligned with respective ones of the PCB stators.
 3. Thedevice of claim 1, further comprising one or more of the following: a)Shims between the flanges of the shaft and the rotor disks to adjust theair gaps between the rotor disks and the PCB stators; b) The rotor diskshave tapered surfaces inboard of the magnets; c) The inner diameteredges of the PCB stators are tapered to form a wedge profile; d) The PCBstators are segmented; e) The rotor disks comprise a soft magneticmaterial; f) The motor disks comprise a non-magnetic material; g) Themagnets on the rotor disks are arranged in a Halbach array configurationwith two magnets per pole with a first magnet oriented perpendicular toa plane of a respective rotor disk and a second magnet orientedperpendicular to the first magnet; h) The magnets on the rotor disks arearranged in a Halbach array configuration with four magnets per polewith a first magnet oriented perpendicular to a plane of a respectiverotor disk and a second magnet oriented perpendicular to the firstmagnet and interspersed with a third magnet and a fourth magnet orientedat 45 degrees relative to the first magnet; i) Inductors inside thehousing that are connected in series with the PCB stators j) Radialchannels located in the shaft configured to dispense the liquid coolantto cool the inductors; or k) A sump located in the housing that isconfigured to collect the liquid coolant.
 4. The device of claim 1,wherein the radial channels that dispense the liquid coolant aresubstantially aligned with air gaps between the PCB stators and therotor disks.
 5. The device of claim 1, further comprising shims betweenthe flanges of the shaft and the rotor disks to adjust the air gapsbetween the rotor disks and the PCB stators.
 6. The device of claim 1,wherein the shaft is connected to a source of liquid coolant by means ofa rotary connector coupled to the shaft
 7. The device of claim 1,wherein the rotor disks have tapered surfaces inboard of the magnets. 8.The device of claim 1, wherein inner diameter edges of the PCB statorsare tapered to form a wedge profile.
 9. The device of claim 1, whereinthe rotor disks comprise a soft magnetic material.
 10. The device ofclaim 1 where the rotor disks comprise a non-magnetic material.
 11. Thedevice of claim 1, wherein the rotor disks comprise carbon fibercomposite.
 12. The device of claim 1, wherein the magnets on the rotordisks are arranged in a Halbach array configuration with two magnets perpole with a first magnet oriented perpendicular to a plane of arespective rotor disk and a second magnet oriented perpendicular to thefirst magnet.
 13. The device of claim 1, wherein the magnets on therotor disks are arranged in a Halbach array configuration with fourmagnets per pole with a first magnet oriented perpendicular to a planeof a respective rotor disk and a second magnet oriented perpendicular tothe first magnet and interspersed with a third magnet and a fourthmagnet oriented at 45 degrees relative to the first magnet.
 14. Thedevice of claim 1, further comprising inductors inside the housing thatare connected in series with the PCB stators.
 15. The device of claim14, wherein the shaft has radial channels configured to dispense theliquid coolant to cool the inductors.
 16. The device of claim 1, whereinthe housing comprises a sump that is configured to collect the liquidcoolant.
 17. An axial field rotary energy device, comprising: a housing;rotor disks having an axis of rotation and rotatably coupled to thehousing, each rotor disk comprises magnets on at least one side of therotor disk, and the magnets on the rotor disks are arranged in a Halbacharray configuration with a plurality of magnets per pole; one or moreprinted circuit board (PCB) stators located axially between the rotordisks and coupled to the housing, each PCB stator comprises layers, andeach layer comprises coils, wherein a number of the rotor disks is equalto a number of the PCB stators plus one, and the PCB stators areinterleaved with the rotor disks; a shaft coupled to the rotor disks andthe housing, the shaft has a hollow section configured to be coupled toa source of a liquid coolant and to radial channels in the shaft thatare substantially aligned with respective air gaps between the PCBstators and the rotor disks to dispense the liquid coolant between therotor disks and PCB stators; and the shaft has flanges configured toreceive the rotor disks.
 18. The device of claim 17, further comprisingone or more of the following: a) Shims between the flanges of the shaftand the rotor disks to adjust the air gaps between the rotor disks andthe PCB stators; b) The rotor disks have tapered surfaces inboard of themagnets; c) The inner diameter edges of the PCB stators are tapered toform a wedge profile; d) The PCB stators are segmented; e) The rotordisks comprise a soft magnetic material; f) The motor disks comprise anon-magnetic material; g) The magnets on the rotor disks are arranged ina Halbach array configuration with two magnets per pole with a firstmagnet oriented perpendicular to a plane of a respective rotor disk anda second magnet oriented perpendicular to the first magnet; h) Themagnets on the rotor disks are arranged in a Halbach array configurationwith four magnets per pole with a first magnet oriented perpendicular toa plane of a respective rotor disk and a second magnet orientedperpendicular to the first magnet and interspersed with a third magnetand a fourth magnet oriented at 45 degrees relative to the first magnet;i) Inductors inside the housing that are connected in series with thePCB stators j) Radial channels located in the shaft configured todispense the liquid coolant to cool the inductors; or k) A sump locatedin the housing that is configured to collect the liquid coolant.
 19. Thedevice of claim 17, wherein the rotor disks comprise a non-magneticmaterial.
 20. The device of claim 17, wherein each rotor disk comprisestwo magnets per pole with a first magnet oriented perpendicular to aplane of a respective rotor disk and a second magnet orientedperpendicular to the first magnet.
 21. The device of claim 17, whereineach rotor disk comprises four magnets per pole with a first magnetoriented perpendicular to a plane of a respective rotor disk and asecond magnet oriented perpendicular to the first magnet andinterspersed with a third magnet and a fourth magnet oriented at 45degrees relative to the first magnet.
 22. The device of claim 17,further comprising inductors inside the housing that are connected inseries with the PCB stators, and the shaft has radial channelsconfigured to dispense the liquid coolant to cool the inductors.
 23. Anaxial field rotary energy device, comprising: a housing; rotor diskshaving an axis of rotation and rotatably coupled to the housing, andeach rotor disk comprises a magnet on at least one side of the rotordisk; one or more printed circuit board (PCB) stators located axiallybetween the rotor disks and coupled to the housing, each PCB statorcomprises layers, and each layer comprises coils, wherein a number ofthe rotor disks is equal to a number of the PCB stators plus one, andthe PCB stators are interleaved with the rotor disks; a shaft coupled tothe rotor disks and the housing, the shaft has a hollow sectionconfigured to be coupled to a source of a liquid coolant and to radialchannels in the shaft that are substantially aligned with respectiveones of the PCB stators to dispense the liquid coolant directly on thePCB stators; and the shaft has flanges to receive the rotor disks. 24.The device of claim 23, further comprising one or more of the following:a) Shims between the flanges of the shaft and the rotor disks to adjustthe air gaps between the rotor disks and the PCB stators; b) The rotordisks have tapered surfaces inboard of the magnets; c) The innerdiameter edges of the PCB stators are tapered to form a wedge profile;d) The PCB stators are segmented; e) The rotor disks comprise a softmagnetic material; f) The motor disks comprise a non-magnetic material;g) The magnets on the rotor disks are arranged in a Halbach arrayconfiguration with two magnets per pole with a first magnet orientedperpendicular to a plane of a respective rotor disk and a second magnetoriented perpendicular to the first magnet; h) The magnets on the rotordisks are arranged in a Halbach array configuration with four magnetsper pole with a first magnet oriented perpendicular to a plane of arespective rotor disk and a second magnet oriented perpendicular to thefirst magnet and interspersed with a third magnet and a fourth magnetoriented at 45 degrees relative to the first magnet; i) Inductors insidethe housing that are connected in series with the PCB stators j) Radialchannels located in the shaft configured to dispense the liquid coolantto cool the inductors; or k) A sump located in the housing that isconfigured to collect the liquid coolant.
 25. An axial field rotaryenergy device, comprising: a housing; rotor disks having an axis ofrotation and rotatably coupled to the housing, each rotor disk comprisesmagnets on at least one side of the rotor disk, and the magnets on therotor disks are arranged in a Halbach array configuration with aplurality of magnets per pole; one or more printed circuit board (PCB)stators located axially between the rotor disks and coupled to thehousing, each PCB stator comprises layers, and each layer comprisescoils, wherein a number of the rotor disks is equal to a number of thePCB stators plus one, and the PCB stators are interleaved with the rotordisks; a shaft coupled to the rotor disks and the housing, the shaft hasa hollow section configured to be coupled to a source of a liquidcoolant and to radial channels in the shaft that are substantiallyaligned with respective ones of the PCB stators to dispense the liquidcoolant directly on the PCB stators; and the shaft has flangesconfigured to receive the rotor disks.
 26. The device of claim 25,further comprising one or more of the following: a) Shims between theflanges of the shaft and the rotor disks to adjust the air gaps betweenthe rotor disks and the PCB stators; b) The rotor disks have taperedsurfaces inboard of the magnets; c) The inner diameter edges of the PCBstators are tapered to form a wedge profile; d) The PCB stators aresegmented; e) The rotor disks comprise a soft magnetic material; f) Themotor disks comprise a non-magnetic material; g) The magnets on therotor disks are arranged in a Halbach array configuration with twomagnets per pole with a first magnet oriented perpendicular to a planeof a respective rotor disk and a second magnet oriented perpendicular tothe first magnet; h) The magnets on the rotor disks are arranged in aHalbach array configuration with four magnets per pole with a firstmagnet oriented perpendicular to a plane of a respective rotor disk anda second magnet oriented perpendicular to the first magnet andinterspersed with a third magnet and a fourth magnet oriented at 45degrees relative to the first magnet; i) Inductors inside the housingthat are connected in series with the PCB stators j) Radial channelslocated in the shaft configured to dispense the liquid coolant to coolthe inductors; or k) A sump located in the housing that is configured tocollect the liquid coolant.